(CNN) -- Since its debut in late June, Google+ has captured much of the tech world's online conversation.

The chatter is generally positive, with tech bloggers cheering Google's new social network as a cleaner and more robust alternative to Facebook. But there have been some bumps on the road.

Over the weekend, Google admitted to inadvertently "spamming" some Google+ users with notification e-mails -- the messages the company sends out if another user adds you to their "circles" of contacts on the site or comments on one of your posts.

Instead of sending those notes out only once, as intended, Google+ sent them "over and over again," writes Google's Vic Gundotra in a post on his Google+ page.

"Thank you for helping us during this field trial, and once again, we are very sorry for the spam," the Google vice president wrote Saturday.

Most Google+ users seemed quick to forgive the slip-up.

"No worries Vic. Keep up the good work! Looking forward to more improvements!" one user wrote in a reply to the apology.

"It's alright, man! :D You rocks!" said another.

Gundotra chalked the spam up to growing pains.

"For about 80 minutes we ran out of disk space on the service that keeps track of notifications. Hence our system continued to try sending notifications. Over, and over again. Yikes," he wrote. "We didn't expect to hit these high thresholds so quickly, but we should have."

It's unclear exactly how many people have joined Google+, and the service undoubtedly has far, far fewer users than Facebook, which leads the field with 750 million users. The fact that the Google+ community is still relatively small is no surprise for two reasons: First, the site is so new; and second, it still isn't public, meaning you have to get a personal invitation in order to sign up -- at least for now.

But it's clear that the new, non-Facebook social network has attracted enough attention that it's growing rather quickly, setting it apart from Google's other attempts to start a social network. Google+ already has more than 4.5 million users, according to one analyst, Paul Allen, who used census data about surnames to make his calculation.

One problem with this rapid growth, as the Google spam shows, is technical. It's hard to make a new network work perfectly if it's expanding too quickly. Google has used this logic repeatedly to justify its limited-invite approach, instead of letting anyone on the Internet join the network.

Another issue, however, is social. At first, a limited network like Google+ feels intimate -- just as Facebook did before nonuniversity users could join it. But with growth comes change, and that could leave some Google+ users feeling that their cozy private party has been transformed into the county fair.

Finally, Google+ users have been pointing out features of other social networks that either don't exist on Google+ or aren't easy to use.

One is the idea of "institution pages," which, on Facebook and Twitter, let companies put out info about new products, news stories and such. There's no such feature to date on Google's new social network, although Google has said that it's working on adding this.

Another is celebrity verification.

On Twitter, for example, if you go to Lady Gaga or Justin Bieber's profile page, there's a little "verified account" badge next to the name, which is a signal to visitors that it's actually the account of a celebrity.

On Google+, it's unclear if accounts are real or fake.

Facebook CEO Mark Zuckerberg's Google+ page stirred up news on the blogosphere because it's interesting that the leader of a competing social network would join this new service, and because it was unclear if his page was real. Blogger Robert Scoble cleared this up in a text message conversation with Zuckerberg, who said that this was indeed his Google+ account.

Similar authenticity issues have popped up with the Google+ pages of Kanye West, Nancy Pelosi and Michael Dell, among others.

"While it's understandable that a verification system was not at the forefront of Google's mind when preparing to launch the network, it looks like one is desperately needed now. We want to be able to tell the real stars from the fakes, so we're not wasting our time. Or even better -- maybe there should be a way for the fakes to never exist in the first place."

For its part, Google continues to say additional updates are coming.

And, in comments to those pleas for patience, users generally seem to believe that the benefits of the service will be worth the wait.